Wind power is considered one of the cleanest, most environmentally friendly energy sources presently available, and wind turbines have gained increased attention in this regard. However, while being considered environmentally safe, wind turbines can pose a threat to bats. Specifically, it has been found that bats may have trouble detecting the rotating rotor blades of a wind turbine or may even be attracted to the wind turbine. As a result, bats can be struck by the rotor blades and killed. The occurrence of such bat strikes have led many to enact regulations and/or laws prohibiting and/or discouraging the placement of wind turbines in areas of high bat populations and/or restricting the operation of wind turbines at night.
Many believe that ultrasonic sound in the frequency range of about 25 kHz to about 100 kHz may be effective at deterring bats by interfering with both the bats' natural sonar and their ability to hunt insects. However, generating enough sound to cover the entire rotor diameter of a wind turbine has proven to be a difficult task. For example, previous attempts have focused on the use of speakers mounted on the nacelle. Unfortunately, due to dissipation of the sound, it has been found that nacelle mounted speakers do not provide for sufficient bat deterrence.
Accordingly, methods and apparatus for producing ultrasonic sound emissions that are capable of producing sufficient acoustic power to deter bats from a wind turbine would be welcomed in the technology.